This invention is directed to a composite, high density plastic sheet material used in the manufacture of a water, dust, wind, air and sound barrier and method of making same. The invention is particularly suited for use in the manufacture of automotive vehicle door panels and will be described with reference thereto, however, as will become apparent, the invention is capable of broader application and could equally well be used as a lightweight sound barrier shield or vibration dampener.
It is known that surface protectors or deflectors are particularly suited for shielding the inner panels of vehicles against the infiltration of water or dust. In general, the deflectors comprise a thin, flexible sheet of a plastic material having a peripheral shape to overlie a predetermined portion of the inner door sheet metal. Typically, the deflectors are joined to the door sheet metal by pressure sensitive adhesive applied in a band around the peripheral edge of the deflectors.
There has been an ongoing need for the flat deflectors to include bulges or pockets to allow them to adequately accommodate radio speakers, door panel clips and similar devices which extend inwardly or outwardly of the door from the inner panel. Typically, the sheet results from a thermoforming operation. These prior attempts have not been altogether successful, especially when the sheet must be cured, stacked, and provided with the adhesive.
Further, the plastic deflectors have not been altogether satisfactory in preventing noise transmission (e.g., tire noises).
The subject invention provides a structure and method of forming the same which overcome the above-noted problems and others in an economical manner.
In accordance with the subject invention, a suitable barrier against water, sound, dust and air comprises a mixture of an inorganically filled thermoplastic elastomer intimately blended with a suitable polyethylene, such as those characterized as being a low density polyethylene (LDPE), or a linear low density polyethylene (LLDPE), or an ultra-low density polyethylene (ULDPE). In accordance with one aspect of this invention, the barrier is cold-formed to include a bulge or pocket like area. In accordance with another aspect of this invention, the barrier is formed (e.g., laminated) to include a separate layer of a low surface energy polymer, such as the low density polyethylene, or treated with silicone release coating, whereby the barriers can be stacked for dispensing. In accordance with yet another aspect of the invention, the barrier can form a deflector against sound and water.
Advantageously, the barrier can be formed by single extrusion or coextrusion processes that are known in the art and thus allowing the user to utilize known forming techniques and apparatus.
A further advantage is provision in one product the sound, water, dust, air, wind, ease of installation, and cost benefits.
A further advantage is provision of a composite sheet which is not only flexible but also somewhat limp, whereby to deaden sound transmission loss in both the low as well as the high frequency ranges. Although the composite sheet is relatively flexible, it is still sufficiently rigid to function as a barrier but the limp nature of the sheet minimizes vibration of its own thereby preventing harmonic vibration such as that caused by speakers.
A further advantage is provision of a barrier of the type described having a plurality of pockets or bulges for use in vehicle door panels wherein the user utilizes the bulges to position the barrier on the door during installation.
Advantageously, the bulge can be cold-formed whereby post curing difficulties are obviated. Desirably so, such as where the bulge is somewhat cone-shaped, the material thickness can be maintained of generally uniform thickness and does not tend to have thinned regions of reduced strength.
The above and other advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following description.